(2) If the magnetic lines of force are at right angles to che longitudinal direction of the wire projecting into the field, the tractive force at right angles to the lines of force is smaller in iron than the force p#. The ratio p#/P1 (where p# and pl are the tractive forces parallel and at right angles to the lines of force respectively), which with mean strengths (about H=100) is greater than 100, rapidly decreases as the field increases and appears to approach unity-Wiedemann's Annalen, No. 1, 1895. . ON THE INFLUENCE OF MAGNETIZATION ON THE CONSTANTS OF ELASTICITY IN IRON. BY A. BOCK. The result of this research is stated as follows by the author :By magnetization the constants of elasticity of soft iron, the modulus of torsion, and the modulus of elasticity are certainly not altered by more than 3 per cent. The series of observations indicate that the flexure diminishes, at the same time the torsion seems also to diminish, while the ratio of the lateral contraction to the longitudinal expansion increases. Iron is more incom. pressible in the magnetic field. Nothing can be alleged with certainty as to magnetized steel bars. These results are in perfect agreement with the well-known investigations of G. Wiedemann, and they may be deduced from the theory propounded by that author on the assumption of rotating molecular inagnets.-Wiedemann's Annalen, No. 3, 1895. K ON THE MAGNETIZATION OF IRON BY VERY SMALL FORCES. BY WERNER SCHMIDT. The experimental results of this research are given by the author in the following statements : 1. Steel follows small magnetizing forces more rapidly than iron. 2. The magnetization function « of mild steel is greater for small forces than that of iron. In the present case « (steel) is to k (iron) as 4 is to 3. The stronger magnetization ordinarily observed in iron is only met with in greater magnetizing forces, for instance, H>1. 3. The constancy of the magnetizing function « for very small forces, first observed by Lord Rayleigh, is confirmed. The boundary of proportionality between magnetizing forces and magnetic moments may be taken with sufficient accuracy for technical purposes as near the magnetizing force H,=0.06. This value represents a rather sudden transition in the curve k=f(H). Below this the deviations from proportionality are only very feeble, that is the curve k=f(H) passes into a parallel to the H-axis. The point at which it can be identified with a straight line (parallel) is different according to the nature of the iron investigated, and especially according to the sensitiveness of the apparatus used for the measurements, without varying much from a certain mean value which may be regarded as lying between the magnetizing forces H,=0.03 and 0·0+.- Wiedemaun's Annalen, No. 4, 1895. INDEX to VOL. XXXIX. 225; some, 447. crust, 93. ACOUSTICAL experiments, on Analytischen Chemie, Crookes's Select Methods in Che- in the medium separating electri- 305 ; Kennedy's A Few Chapters fied or gravitating particles, 357. in Astronomy, 307; Geikie's The to the Antiquity of Man, 379. of, 534. illustration of the determinantal perature on the specific heat of, Burke (J.) on the luminescence of glass due to kathode rays, 115. and dispersion of electrical rays, cal experiments, 447. Calorimetry, on the use of aniline as Carbonic acid, on an experiment apparatus for determining the Combination of substances in the 160; on tests of glow-lamps, 389. heat of, 510. of, 341, 452 netic fields on the electrical con- ballistic-galvanometer method of determining the electromagnetic the geology of the Harlech area, Cooke (J. H.) on the Pleistocene beds of the Maltese islands, 542. atomic heat in the periodic series spectra of, 124. Crystals, on the rotational coefficients netization on the constants of Cubes, on Ronayne's, 183. Currents, on some experiments with of the Narborough district, 543. Deeley (R.M.) on glacier-grains, 453. duction to Physical Measurements, of gases, 298. Dielectric power of ice, on the, 144. Green (Prof. A. H.) on some recent Gresley (W. S.) on the Midland the Lake Superior Region, 547. Griffiths (E. H.) on the influence of temperature on the specific heat of aniline, 47, 143. of, 367. Haycraft (H. C.) on a simple appa- on, 529. ratus for determining the mecha- nical equivalent of heat, 160. termining the mechanical equiva- denser, on a modification of the of the motion of, 501. in the liquid and solid condition, on the, 510. Helmholtz's electrochemical theory, in the periodic series of the, 106. Henderson (J. B.) on the influence separating electrified or gravitating conductivity of bismuth, 143, Hennessy (Prof. H.) on Ronayne's cubes, 183. 387. ductive capacities of water, alco- Hydrogen, on the critical pressure of, dispersion of electrical rays, 144. Ice, on the dielectric power of, on the velocity of sound in, 142; Iron, on the influence of magnetiza- by very small forces, 548. in soft, placed in a uniform mag- netic field, 226. stress, 254. Korteweg (Prof. D.J.) on the change of form of long waves advancing in a rectangular canal, and on a 422. some dynamical theories of, 145. of South Denbighshire, 141. 199. 6 Larmor (J.) on the significance of Olszewski (Prof. C.) on the liquefac- Wiener's localization of the pho- tion of gases, 188. of an, through a plate of conduct- , absorption spectrum and colour of Paraffin, on the specific inductive rapidly changing fields, 78. the rôle of atomic heat in the, 106. magnetic, for rapid electrical os- Perot (A.) on the dielectric power Outlines of Quaternions,' 135. light-waves, on the, 97. length in soft iron wire placed in for surveying by means of, 544. Pickering (S. U.) on the heat of for rapid electrical oscillations, liquid and solid condition, 510. Pitch, on the subjective lowering of, 447. tween electromagnetic stress and, the dimensions of a body on its of gravitation, 145. with solid carbonic acid, 308. k=N-1=-i=-;= -k in, 135. simple apparatus for determining 460. Resistance, on the measurement of, Richarz (F.) on Helmholtz's electro- interpretation of the dissipation in soft iron wire placed in a uni- 341. fossils from Madagascar, 543. with alternating currents, 377. comparing the values of the specific magnetic permeability for rapid of iron by very small forces, 548. on a ne- Schnyder von Wartensee prize Thompson (Prof. S. P.) on mirrors of magnetism, 213; on ment of resistance, 175; on the 534. when producing a current, 295. producing a current, 375; on the Vries (Dr. G. de) on the change of tin-chromic chloride cell, 444. form of long waves advancing in type of long stationary waves, 422. cients of thermal conductivity in Waves, on the change of form of long, advancing in a rectangular stationary, 422. stance under slowly and rapidly oscillator, through a plate of con- tive force, 547. the ballistic-galvanometer method capacity of a condenser, 172. plate of conducting dielectric, 309; analyser, 367. END OF THE THIRTY-NINTH VOLUME. 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